Name ___________________________________________________ Date _____________
MARINE SCIENCE
SHARK DISSECTION LAB
Spiny Dogfish
Squalus acanthias
Introduction
Spiny dogfish (Squalus acanthias) are one of the most common species of sharks
in the world. Their name comes from the fact that they hunt in very large shoals,
or “packs”, like dogs. These shoals can sometimes number in the hundreds or
even thousands. The “spiny” part of their name comes from the two dorsal
spines found in front of their dorsal fins. These are used defensively. If captured,
the shark can arch its back to pierce its captor, while glands at the base of the
spines secrete a mild poison. They are found mostly in shallow waters and
further offshore in most parts of the world, especially in temperate waters. You
can find spiny dogfish off the coast of Long Island during the summer months.
Spiny dogfish are small. Males mature at around 11 years of age, growing to a
length of 2.5 to3 feet. Females mature in 18–21 years and are slightly larger than
males, reaching 3 to 5 feet in length. Both sexes are greyish brown in color and
are counter-shaded. Males are identified by a pair of pelvic fins modified as
sperm-transfer organs, or claspers. The male inserts one clasper into the female
cloaca during mating. Immediately after fertilization, the eggs become
surrounded in egg cases (several eggs per case). The female will carry these
eggs for almost two years before they hatch. With estimates of between 20 and
75 years, the spiny dogfish is thought to be a very long-lived fish.
The spiny dogfish is an opportunistic feeder, eating whatever prey is abundant.
In general their diet is comprised of small fishes such as capelin, haddock, and
herring. They also eat invertebrates such as krill, crabs, worms, jellyfish, , squid
and octopuses. They are preyed upon by cod, red hake, goosefish, other spiny
dogfish, larger sharks, seals, orcas, and humans.
Systems we will look at
In this dissection, we will first view the external anatomy of the shark. This
includes the dental teeth of the skin, its fins, dorsal spines, mouth, and cloaca. In
the shark’s mouth, you will find tiny teeth. If you carefully (carefully!) poke your
fingers in, you should be able to feel the different rows of teeth. By looking for
the presence or absence of claspers, you will be able to determine if your
specimen is male or female.
We will also view parts of their circulatory system, in particular the heart and
blood vessels. In your specimen, you will notice that the blood vessels are
stained either red or blue. Red indicates arteries, blood vessels that carry blood
away from the heart to deliver oxygen to the shark’s cells and tissues. Blue
indicated veins, blood vessels that carry blood back to the heart after delivery
of oxygen to cells and tissues.
Finally, we will find the anatomical structures that are part of the shark’s
digestive system. Beside the stomach and intestines, we will also look for the
pancreas, liver, spleen, and rectal gland.
Materials
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Preserved dogfish shark (Squalus acanthias)

Dissecting tray
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Dissecting scissors
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Dissecting probe
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Safety scalpel
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Forceps
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Pins
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Gloves
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Dissecting microscope
Safety Precautions

Scalpels, dissecting scissors, dissecting probes, and pins are all sharp
instruments. Use caution when handling.

Always cut away from yourself and others.

Secure the specimen in the dissecting tray before cutting anything.

Wear safety goggles and gloves.

Wash hands thoroughly with soap and water before leaving the lab.

LISTEN CAREFULLY AND QUIETLY TO ALL TEACHER INSTRUCTIONS
Procedure
Carefully follow the directions as they are given by your teacher. Make sure you
understand what you should be doing at all times – if you don’t know, then just
ask.
Diagrams
Figure 1. External anatomy
Figure 2. Proper incisions for viewing internal anatomy
(ventral side)
Figure 3. Digestive system
Figure 4. Male reproductive system
Figure 5. Female reproductive system
POST LAB DIAGRAMS
Part 1: External Anatomy Diagram
Use the space below to draw a detailed, labeled sketch of the external
anatomy of the shark (you can turn the page if it is more convenient).
Part 2: Internal Anatomy Diagram
Use the space below to draw a detailed, labeled sketch of the internal anatomy
of the shark (you can turn the page if it is more convenient).